1.\" Copyright (c) 1990, 1991, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 3. Neither the name of the University nor the names of its contributors 13.\" may be used to endorse or promote products derived from this software 14.\" without specific prior written permission. 15.\" 16.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 17.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 20.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26.\" SUCH DAMAGE. 27.\" 28.Dd February 8, 2024 29.Dt REBOOT 8 30.Os 31.Sh NAME 32.Nm reboot , 33.Nm halt , 34.Nm fastboot , 35.Nm fasthalt 36.Nd stopping and restarting the system 37.Sh SYNOPSIS 38.Nm halt 39.Op Fl DflNnpq 40.Op Fl e Ar variable=value 41.Op Fl k Ar kernel 42.Op Fl o Ar options 43.Nm 44.Op Fl cDdflNnpqr 45.Op Fl e Ar variable=value 46.Op Fl k Ar kernel 47.Op Fl o Ar options 48.Nm fasthalt 49.Op Fl DflNnpq 50.Op Fl e Ar variable=value 51.Op Fl k Ar kernel 52.Op Fl o Ar options 53.Nm fastboot 54.Op Fl dDflNnpq 55.Op Fl e Ar variable=value 56.Op Fl k Ar kernel 57.Op Fl o Ar options 58.Sh DESCRIPTION 59The 60.Nm halt 61and 62.Nm 63utilities flush the file system cache to disk, send all running processes 64a 65.Dv SIGTERM 66(and subsequently a 67.Dv SIGKILL ) 68and, respectively, halt or restart the system. 69The action is logged, including entering a shutdown record into the user 70accounting database. 71.Pp 72The options are as follows: 73.Bl -tag -width indent 74.It Fl c 75The system will turn off the power and then turn it back on if it can. 76If the power down action fails, the system 77will halt or reboot normally, depending on whether 78.Nm halt 79or 80.Nm 81was called. 82At the present time, only the 83.Xr ipmi 4 84driver implements the power cycle functionality and only on hardware 85with a BMC that supports power cycling. 86Unlike power off, the amount of hardware that supports power cycling 87is small. 88.It Fl D 89Delete existing 90.Nm nextboot 91configuration and exit. 92.It Fl d 93The system is requested to create a crash dump. 94This option is 95supported only when rebooting, and it has no effect unless a dump 96device has previously been specified with 97.Xr dumpon 8 . 98.It Fl e Ar variable=value 99Sets 100.Va variable 101to 102.Va value 103in the loader's and kernel's environment. 104If 105.Va value 106is not already enclosed in double quotes, they will be added before writing to the 107.Nm nextboot 108configuration. 109Care should be taken if 110.Va value 111contains any characters that are special to the shell or loader's configuration 112parsing code. 113.It Fl k Ar kname 114Boot the specified kernel 115.Ar kname 116on the next system boot. 117This is a one-shot option, the 118.Em default 119kernel will be booted on successive boots. 120No 121.Nm reboot 122or 123.Nm halt 124will be performed if 125.Em /boot/kname/kernel 126does not exist unless the 127.Fl f 128flag is specified. 129.It Fl l 130The halt or reboot is 131.Em not 132logged to the system log. 133This option is intended for applications such as 134.Xr shutdown 8 , 135that call 136.Nm 137or 138.Nm halt 139and log this themselves. 140.It Fl N 141The file system cache is not flushed during the initial process clean-up, 142however the kernel level 143.Xr reboot 2 144is still processed with a sync. 145This option can be useful for performing a 146.Dq best-effort 147reboot when devices might be unavailable. 148This can happen when devices have been disconnected, such as with 149.Xr iscsi 4 . 150.It Fl n 151The file system cache is not flushed. 152This option should probably not be used. 153.It Fl o Ar options 154This option 155allows the passing of kernel flags for the next boot. 156.It Fl p 157The system will turn off the power if it can. 158If the power down action fails, the system 159will halt or reboot normally, depending on whether 160.Nm halt 161or 162.Nm 163was called. 164.It Fl q 165The system is halted or restarted quickly and ungracefully, and only 166the flushing of the file system cache is performed (if the 167.Fl n 168option is not specified). 169This option should probably not be used. 170.It Fl r 171The system kills all processes, unmounts all filesystems, mounts the new 172root filesystem, and begins the usual startup sequence. 173After changing vfs.root.mountfrom with 174.Xr kenv 1 , 175.Nm Fl r 176can be used to change the root filesystem while preserving kernel state. 177This requires the 178.Xr tmpfs 5 179kernel module to be loaded because 180.Xr init 8 181needs a place to store itself after the old root is unmounted, but 182before the new root is in place. 183.El 184.Pp 185The 186.Nm fasthalt 187and 188.Nm fastboot 189utilities are nothing more than aliases for the 190.Nm halt 191and 192.Nm 193utilities. 194.Pp 195Normally, the 196.Xr shutdown 8 197utility is used when the system needs to be halted or restarted, giving 198users advance warning of their impending doom and cleanly terminating 199specific programs. 200.Sh EXAMPLES 201Replace current root filesystem with UFS mounted from 202.Pa /dev/ada0s1a : 203.Bd -literal -offset indent 204kenv vfs.root.mountfrom=ufs:/dev/ada0s1a 205reboot -r 206.Ed 207.Pp 208This mechanism can also be used with NFS, with a caveat that 209it only works with NFSv4, and requires a numeric IPv4 address: 210.Bd -literal -offset indent 211kenv vfs.root.mountfrom=nfs:192.168.1.1:/share/name 212reboot -r 213.Ed 214.Sh SEE ALSO 215.Xr kenv 1 , 216.Xr getutxent 3 , 217.Xr ipmi 4 , 218.Xr boot 8 , 219.Xr dumpon 8 , 220.Xr nextboot 8 , 221.Xr savecore 8 , 222.Xr shutdown 8 , 223.Xr sync 8 224.Sh HISTORY 225A 226.Nm 227utility appeared in 228.Bx 4.0 . 229